This invention relates to phosphors for plasma display panels. More particularly, this invention relates to phosphors which are used to generate the red primary color in full color plasma display panels.
In order to achieve full color reproduction, a plasma display panel (PDP) is composed of pixels which emit light corresponding to the three primary colors of red, green and blue. The pixels are formed from red-, green-, and blue-emitting phosphors which have been deposited on an inner wall of the device. The tri-color emission is achieved by stimulating the phosphors with vacuum ultraviolet (VUV) radiation generated by Xexe2x80x94Ne gas discharges (172 nm). The luminous efficiency, color chromaticity, afterglow, and stability of the phosphors have significant roles in the PDP performance.
Typical phosphors used in PDP applications include a red-emitting (Y,Gd)BO3:Eu phosphor (YOB), a green-emitting Zn2SiO4:Mn phosphor, and a blue-emitting BaMgAl10O17:Eu. The red-emitting (Y,Gd)BO3:Eu phosphor exhibits good brightness under VUV excitation but its emission color is slightly orange (x=0.642, y=0.358) because of its strong emission at 592 nm. Since a redder color is preferred, Y2O3:Eu has in the past been considered for use as the red-emitting phosphor because of its single emission peak at 612 nm (x=0.652, y=0.347). Unfortunately, Y2O3:Eu exhibits a much lower brightness than YOB because of lower absorption at 172 nm.
In order to eliminate produce a redder color, a typical PDP employs an active color correcting (ACC) filter which has an absorption at about 600 nm. The ACC filter provides a dual benefit in that it absorbs both the 592 nm emission of YOB and the red 585 nm emission generated by the neon gas in the Xexe2x80x94Ne discharges. FIG. 1 illustrates the effect of the ACC filter on the emissions of a typical PDP. Although this results in better red color saturation, some of the brightness benefit provided by the YOB phosphor is lost.
It is an object of the invention to obviate the disadvantages of the prior art.
It is another object of the invention to provide a red-emitting phosphor blend for plasma display panels.
In accordance with one aspect the invention, there is provided phosphor blend comprising a mixture of a first red-emitting phosphor having a general formula of (Y1-x-yGdxEuy)2O3 wherein 0xe2x89xa6xxe2x89xa60.9 and 0.02xe2x89xa6yxe2x89xa60.4 and a second red-emitting phosphor having a general formula of (Y1-a-bGdaEub)BO3 wherein 0xe2x89xa6axe2x89xa61 and 0.02xe2x89xa6bxe2x89xa60.1, the second red-emitting phosphor comprising from 10 to 40% by weight of the blend.